Project Summary The parent project for this supplement, based within a prospective longitudinal pre-birth cohort study (Project Viva) that includes data from early pregnancy through adolescence, is focused on characterizing how children?s trajectories of growth and adiposity may change as they traverse adolescence, with a primary goal to identify and quantify modifiable determinants of these changes. The goal of the proposed supplement is to characterize the association between maternal nutritional patterns during pregnancy and childhood growth trajectories through adolescence, with particular emphasis on disentangling the roles of maternal and child stress. Children with excess adiposity are at increased risk for adverse health outcomes in adulthood. Programming of child obesity is likely multifactorial with a nuanced interplay between pre-, peri-, and postnatal factors. We and others have reported associations of prenatal nutrition and dietary inflammation with childhood adiposity and obesity through mid-childhood. However, limited longitudinal data through adolescence exists on the associations of maternal nutrition in pregnancy with offspring adiposity trajectories. Furthermore, emerging animal data suggest that fetal exposure to maternal stress ? the prevalence of which is high in the United States ? may program adiposity later in life. There exists a bidirectional relationship between stress and nutrition, however, in humans, it is unknown whether prenatal stress may exacerbate the effects of prenatal nutrition alone on offspring adiposity. In addition, while the mediating role of early childhood stress is unknown in humans, in animals, prenatal nutrition, specifically high fat diet, induces alterations in the offspring hypothalamic-pituitary axis, which may alter the programming of homeostasis and metabolism associated with later obesity risk. Here, we propose to investigate the role of nutrition in pregnancy as predictor of childhood adiposity trajectories and characterize the role of maternal and child stress in these associations. Our overall hypothesis is that from infancy to adolescence, children born to mothers with a highly inflammatory diet in pregnancy will gain weight and adiposity more rapidly compared to children born to mothers with a less inflammatory diet, and that both maternal stress and offspring stress will play a critical role in this association. Specifically, maternal stress will potentiate the effect of an inflammatory diet in pregnancy on offspring adiposity trajectories. Furthermore, offspring cortisol (a marker of chronic stress) will mediate associations of maternal nutrition with adiposity in adolescence. We propose to investigate these associations and underlying mechanisms within the Project Viva cohort, leveraging the detailed nutritional, anthropometric and psychosocial data that has been collected from early pregnancy through adolescence in the mother-infant dyads. The proposed study will contribute to our understanding of the role of maternal nutrition in longitudinal offspring growth and provide novel evidence regarding the intersection of psychosocial stress in this association.